The brain is constantly receiving sensory information from inside of the body, but it is underappreciated how this internal sensory information can affect animal behavior. To address this, we are developing the small transparent fish Danionella cerebrum as a model for brain-body signaling. I will describe our work characterizing the anatomy, molecular subtypes, and sexual dimorphism in D. cerebrum nervous system, especially the visceral sensory neurons. Our current research directions are focused on linking these sexually dimorphic visceral sensory neurons to reproductive behaviors, and I will discuss our recent progress in high throughput behavioral quantification during mating. Ultimately, D. cerebrum presents a unique opportunity to holistically consider how the nervous system responds to cues from inside of the body to generate mating behaviors at the appropriate time.